(a) Field of the Invention
The present invention relates to a method and apparatus for transmitting information in a low latency mobile communication system.
(b) Description of the Related Art
Recently, low latency services requiring a delay time within a few ms have been studied in a mobile communication field. In a cellular wireless access system, low latency services are services in need of mobility, coverage, and reliability provided by a cellular scheme among services considered in the tactile Internet. As automobiles have become smart, application of low latency wireless communication to vehicle-to-vehicle (V2V) or vehicle-to-infrastructure (V2I) low latency wireless communication has come to prominence. In a situation in which various real-time interactive multimedia services such as augmented reality, virtual reality, and real-time online games are increasingly provided, it is required to provide low latency services to allow users of the services to experience natural interactions.
For such low latency services, a short delay time is required in an air interface. To this end, a transmission time interval (TTI) having a length of 1 ms of an existing system (for example, 3GPP LTE-Advanced) is designed to have a short length of tens of us to hundreds of us. For example, it is considered to design a short TTI having a length of 100 us, about 1/10 level of the existing length.
When a system is designed with a short TTI, overhead of control information may be increased. That is, since a transmission period of control information is shortened according to the shortened TTI, the number of transmissions of control information is resultantly increased.
As the number of transmissions of the control information is increased the number for a terminal to receive control information is also increased. For example, in a case in which a TTI has a length as short as about 100 us, the number of reception of control information of the terminal is increased to about 10 times.
Also, when receiving control information, the terminal performs blind decoding on a physical downlink control channel (PDCCH) in every TTI, and as the number of times of receiving control information is increased and a process of receiving and decoding symbols is also increased, power consumption of terminals is further increased.
Meanwhile, in a resource allocation (RA) Type 0, among resource allocation modes currently used in a mobile communication system (LTE), bitmap resource allocation is performed by a resource allocation unit, that is, a resource block group (RGB). A size of the RGB (in RBs) is determined by a system bandwidth, and, for example, a size of RGB is fixed to 4 in a system having a bandwidth of 20 MHz. In a data transmission using a single TTI, when a length of the TTI is significantly reduced, a size of the RGB needs to be increased to enhance resource allocation efficiency.
Also, in case of performing data transmission using several TTIs, resource allocation may need to be performed efficiently using a more minute RGB unit. Also, in the RA Type 2 mode, a continuous resource allocation function of designating a starting RB of resource allocation and an end RB of resource allocation is provided. Even in this method, in case of data transmission using a short TTI, a large amount of bits are required for expressing allocated resources. Thus, it is required to reduce information related to resource allocation.